Greetings from the Night Watch!

Greetings from night-operations onboard the FSV Henry B. Bigelow! Tonight we find ourselves floating above the mouth of the Atlantis sub-marine canyon along the New England shelf break. The Mid-Atlantic and New England continental shelf is home to approximately 70 sub-marine canyons that are important features of the marine environment. Located directly south of Woods Hole, MA, Atlantis canyon was named after the tender ship for the world famous scientific submersible Alvin (which also has a canyon named in its honor) that originally explored much of the deep ocean habitats throughout the northwest Atlantic Ocean.

Sub-marine canyons, such as Atlantis, are deep impressions cut into the seafloor at the continental slope (where the sea floor drops abruptly from several hundred to several thousand feet) and are typically formed through the same processes that formed the Grand Canyon, only under water and not as big. The features of sub-marine canyons make them ideal habitats for a number of deep-sea animals.

The goal of tonight’s work is to sample large groups of zooplankton (copepods, amphipods, and krill) and fish that make daily vertical migrations from the ocean depths (800-1200 feet), where they live during the day, to the surface waters at night to feed. To do this, we use electronics located on the hull of the ship (active acoustics) to locate animals in the water column.

Mesopelagic fishes

Layer 1. Mesopelagic fishes, such as (a) pearlsides and (b) lanternfish, collected at 50 m depth with towed nets.

Once we have located interesting layers that we believe to be zooplankton and fish (Layers 1, 2, and 3), we use special towed nets to collect and identify the animals living in each layer. In this case, we see that small mesopelagic fish, such as lanternfish and pearlsides, while present in all three layers, are the most abundant animals in Layer 1. Layer 2, located between 100 and 200 m depth, is dominated by zooplankton, such as krill and hyperiid amphipods.

Zooplankton

Zooplankton, such as (a) krill and (b) amphipods, collected in Layer 2 (between 100 and 200 meters).

Lastly, our deepest layer (Layer 4) is composed of larger deep-water fish, such as viperfish and snipe eels.

deepwater fish

Deepwater fishes such as (a) viperfish and (b) snipe eel collected in the deep ocean (Layer 3).

Aside from studying animals in the deep ocean, we also get to experiment with the effect of the deep sea on some items that we use in everyday life. Stay tuned until next time when we discuss why it is important to study animals living in sub-marine canyons and the deep ocean and see where our travels take Gumby.

technician Gumby

Honorary survey technician Gumby helps show the effect of pressure at depth on a Styrofoam cup. On the left is your everyday Styrofoam cup while on the right is the same cup after it has traveled to a depth of 1200 m (300 football fields!).

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